Wallboard



July 2, 1940. 1 J. NOVAK 2,206,042

wALLBoARn Filed Dec. e. 1937 annie-:Quim

, 30 Fig. 3 is a. transverse section of va board as it wallboard which will not require a further use of 30 Patented July 2, 1940 y.

UNITED .STATES PATENT OFFICE WALLBOARD lzador J. Novak, TrumbullfConn., assigner to Raybestos-Manhattan, Inc., Bridgeport, Conn., a corporation of New Jersey r i Application December 8, 1937,Serial No. 178,681 y 'z Claims. (ci. 154-2) This invention relatesto improvements in wallat the edges may be suitably trimmed off and the board or plasterboard construction, and parboard cut to proper dimensions. ticularly to a composite structure of gypsum or The liner board sheets Il and I2 are formed of plaster and a liner therefor. fibrous construction by' a paper making machine 5 The object of this invention is to form a liner in conventional manner and may be of varying 5 for gypsum or plasterboard which will readily thicknesses consistent with the intended use or absorb the moisture or water from the gypsum or desired product. Incorporated with the bers plaster and form an adherent and tenacious ybond either by introduction into the pulp in the beater i therewith. or by the wet web or dry web saturation processes,

Another object pertains to the formation of a is sodium silicate, preferably in the proportion of lo f liner board to which gypsum orplaster may be 5% relative to the weight of the fibres. The readily applied and which will readily bond therefelted fibre sheet may be .finished off either by with to form a structure which may be readily calendering both surfaces or one surface, or both handled, will not be fragile, which will not be too of the surfaces may be left uncalendered, dependthick or too bulky, and which may be readily and ing upon the desired characteristics of the wall- 16 quickly set up in use without necessity for addiboard; for example, a smooth calendered surface tional processing. l f may be used when it is desired to apply directly Other objects and advantages will be apparen thereto coating material such as paint or varnish, from consideration of the following specification using a minimum amount of sizing materials,

and description of the drawing, wherein, .or where it is desired ,to apply plastic materials to 20 Fig. 1 is aA perspective view of a fragment of the surface, the sheet `may be left uncalendered so wallboard constructed in accordance with an emas to have a surface wherein the fibres will more bodiment of my invention, showing an inner layer readily interlock with plastic materials and form of gypsum or plaster and outer layers of silicated a stronger bond therewith. If it is desired to fibrous material, parts being cut away to ilcoat or apply the plaster to the fibrous silicated 25 lustrate the composition of the composite strucboard after theboard has been installed orv set in ture. place, a heavier grade of board may be used and Fig. 2 is a section through the board shown in gypsum or plaster of Paris in plastic state applied Fig. 1. thereto. Or if it is desired to form completed leaves a continuous forming machine. l gypsum orl plaster of Paris, the plastic naterial Referring to the drawing, Ill indicates a layer may be sheeted out onto a sheet of silicated fibre of gypsum or plaster `of Paris which has been board or formed between two thin sheets of formed between the layers Il and I2 of silicated silicated fibre board. fibre board to form a completed structure which In addition `to the interlockinglof the fibres of may be readily nailed in place in the form of the fibre board with the pastic material I observe panels or strips. e that the silicated fibre board seems to have an In Fig. 3 is shown a section ofwallboard which affinity for the gypsum or plaster of Paris and has been formed on a continuous forming mathere appears to be a chemical reaction at the chine, the bottom paper layer Il being of greater conjugation of the surface of the silicated fibre width than the upper paper layer I2, the edges I3 board and the gypsum or plaster of Paris so that of the sheet I I having been bent upwardly to form there is formed ybetween the two an interlocking a trough so as to reveice the plasticgypsum and and adherent bond and while the sodium silicate laterally confine it during the setting stage.y As imparts stiffening characteristics to the structhe gypsum is poured into the trough formed by ture, it imparts to the bre board the property of the iower sheet, the upper sheet is immediately absorbing moisture 0r water from the plasterof laid thereon so that the whole may set and bond Paris or gypsum- This abSOIPtiOn 0f Water 2P- together. 'Ihe composite structure or sand pears t0 be blllght abOlli by hydrolysis of the wich is then passed through suitable roller sodium silicate contained in the lfibre board by the means while still wet and plastic'to form a sheet moisture of the plastic gypsum to produce an alka- 50. of uniform thickness and to more firmly conline reaction with the gypsum or plaster of Paris solidate the sheets with the plaster. Then while to form a reaction product therewith. While the still wet'and before the plaster is set it is passed incorporation of sodium silicate with fibre board to a heated dryer to rapidly set the plaster. permits of the use of a thin board, other alkaline After the board has been dried, the'excess paper substances may be used in its place, as for ex- 55 ample, sodium carbonate, lime. trisodium phosphate, etc., but it has been found that with the use of these other alkaline materials a thicker fibre board is necessary which in many instances is not desirable. However, if alkaline materials are used and the pH value maintained above 8, I have found that this absorption of moisture or Water from the plaster by the alkaline substance incorporated with the bre boardwill react with the gypsum or plaster of Paris to assist in firmly uniting the fibre board treated with the alkaline substance or sodium silicate, and the layer of plaster.

This results in a rm unitary structure which may be readily handled without crumbling or breaking, may be readily cut up `into strips and sizes for use and may be readily shipped or stored. It will also be seen that gypsum or plaster of Paris applied after the bre board has been installed in construction work or pre-formed in composite wallboard, will readily and quickly dry in a lesser amount of time than is ordinarily required and will set to form a rm bond throughout the whole. Further, by the use of a felted brous sheet which may have a smooth calendered surface a wallboard is formed which may be fixed in place and the surface thereof immediately decorated in any suitable surface coating manner, or if it is desired to add additional plaster the surface may be left uncalendered.

In the manufacture of the plaster board sandwich, it is formed with the silicate treated board that it is immediately wet by the gypsum paste resulting in good adhesion in contradistinction to ordinary chip board which resists water penetration for a much longer time. This rapid penetration of moisture results in more rapid setting of the gypsum, and more rapid drying of the moisture in the dryer end of the continuous forming machine. It was found that the machine could be speeded up 20% to 30% in practice; Further, because of the added stiffness of the board, .015" thickness could be used in place of .019" ordinary chip or news board, resulting in proportional saving. Plaster applied to the outside of the board after installation in a wall adheres satisfactorily without staining.

I claim as my invention:

1. A wallboard comprising a layer of plaster and a felted fibrous liner therefor, the said liner having incorporated therewith an alkaline substance adapted to absorb moisture from the plaster and upon hydrolysis to form a reaction product of said alkaline substance and plaster product of plaster and sodium silicate upon the resultant hydrolysis thereof.

3. The method of making plaster wallboard which comprises forming a felted fibrous liner sheet having incorporated therewith an alkaline body adapted to have a pH value over 8 upon hydrolysis thereof, and applying a plastic layer of plaster thereto, the said alkaline body being adapted to absorb Water for hydrolysis thereof from said plastic plaster and to form a reaction product therewith of said alkaline body and said plaster, the said reaction product forming a bonding medium between said liner and said plaster.

4. The method of making plaster wallboard which comprises depositing a layer of plastic plaster on a felted fibrous liner sheet comprising sodium silicate, applying a similar liner sheet thereover, the said sheets being adapted by the incorporation therewith of said sodium silicate to absorb'water from the said plastic plaster and to react therewith to form a reaction product of sodium silicate and plaster to firmly unite the sheets to said plaster, and subjecting said plastic mass to heat to rapidly set it and to form a rrnly bonded unitary board.

5. A wallboard comprising an inner core of plaster, and outer plies of felted fibrous material saturated with sodium silicate, and a reaction -product of sodium silicate and plaster formed in situ at the conjugation of the respective ply surfaces.

6. A wallboard comprising a layer of, plaster and a felted brous liner therefor, the said liner comprising sodium silicate, and a reaction prod- 

